A slide valve of this type is, for instance, disclosed in U.S. Pat. No. 3,368,792. Slide valves of this type have proved effective when used in installations containing a pure residual gas atmosphere. However, when a slide valve of this type is used in a vacuum installation which contains a contaminated residual gas atmosphere (condensed vapors, dust particles and the like), contamination of the mechanism which serves for interacting displacement of the sealing plate and counter element and, thereby, its function, cannot be prevented.
To prevent contamination, slide valves of this type were designed in such a manner that the shut-off member is sealed on all sides (U.S. Pat. No. 4,052,036). In this case, metal bellows were provided between the sealing plate and the counter element, forming the shut-off member. This indeed seals off the displacement or adjustment mechanism against the atmosphere surrounding the slide valve on the inside. The disadvantage of this design however lies in that these bellows require relatively large space for housing them and installing them, so that, when viewed in the flow direction of the slide valve, the shut-off member becomes very wide. This is considerably disadvantageous in many applications.
Accordingly, the main object of the invention is to keep the width of the shut-off member as small as possible, so that the slide valve is narrow.